In the manufacture of glass containers by a forming machine of the I.S. ("individual section") type, one or more streams of molten glass flow downwardly from a feeder bowl of a glass melting furnace forehearth toward a section of the molding machine, and each stream is severed or sheared into a multiplicity of individual gobs by a shearing device positioned between the feeder bowl and the molding machine. A typical device of the foregoing character includes opposed sets of shear blades, each set of shear blades being mounted on a carriage assembly, and driving apparatus for reciprocating each of the carriage assemblies toward and away from one another. Various shearing devices of this general character are disclosed in U.S. Pat. No. 4,813,994 (Kulig) and in U.S. Pat. No. 4,499,806 (Mumford), the disclosures of which are incorporated by reference herein. Heretofore, shearing devices as described above utilized externally cooled shear blades, such blades being cooled by an external spray of water or an aqueous animal fat emulsion. However, the use of external cooling for such an application is undesirable because it creates the need, for environmental purposes, to recapture and recycle spent cooling fluid.
It has previously been proposed, for example, in U.S. Pat. No. 3,758,286 (Heyne), the disclosure of which is also incorporated by reference herein, to internally cool the blades of a glass feeder shearing mechanism by circulating a cooling fluid therethrough. However, an internally cooled shear blade inherently must be much thicker than an externally cooled shear blade, and, hence, internally cooled shear blades are considerably more rigid than their externally cooled counterparts. The added rigidity of internally cooled shear blades makes it difficult to maintain a proper contact load between opposed shear blades in their overlapping, shearing positions, because such internally cooled shear blades are incapable of deflecting under load to the same degree as their externally cooled counterparts.